Alternator.



STRATFORD B. ALLEN AND EVERETT T. KING.

OF CAMBRIDGE, MASSACHUSETTS.

ALTERNATOR.

Specification of Letters Patent.

Application ied August 11, 1910.

Patented July 18. 1911-. Serial No. 576,756.

To all whom 'it may concern.'

Be it known that we, S'rna'rro'nn B. ALLEN and lvEnE'r'r T. KING, both citizens of the United States, residing in Cambridge, in the county of Middlesex and State of Massa chusetts, have invented certain new and useful lmprovenients in Alternators, of which the following, taken in connection with the accompanyingdrawings, is a specification.

This invention relates to a device for converting direct current into alternating current. y

)ne object ofthe invention is to provide a device which shall convert direct current into alternating current b y means of mechanical vibration without the use of a rotary converter, 1notorlgenerator, or thelike.

A further object of the invention is to provide a device for converting direct current into alternating current ot comparatively high frequency and suitable for wireless 4tclegral'ihy, Xsray work, or the like,

ll'ith the above objects in View the invention consists in the device of the. character set :forth and as hereinafter described and claimed, the advantages of which will be obvious to those skilled in the artfrom the following'detailed description'. y Y

The accompanying drawing is a diagrammatic plan view of a preferred embodiment ot the invention,

As illustrated in the drawing the device comprises a switch composed of two contact carrying arms each cooperating with a pair ot' opposed adjustable contacts, and electromagnetic means for rapidly oscillating the switch. Condensers are connected across the inakea1nl-break contacts and a condenser is connected across each pair ot' cooperating switch contacts. One function oi. the condcnsers is to reduce sparking y'at the contacts. The condensers across the switch contacts as Ithey discharge after each impulse ot the direct current, when the latter isintelrupted, producen mon'lentary oscillatory current which is opposite in polarity to that ot the direct. current impulse preceding it. The condensers thus located discharge through the instrument in thealternating current Vcircuit and' thus increase the spark produced by the apparatus vat. the interruption ot each alternation. f

The switch l comprises a block 2 of in-` Q and radiatingr at substantially 120 are two contact-carrying arms 4l and 6 provided at their outer or free ends with contacts T, 8, and t), 10, respectively. These contacts are adapted to be brought into contact with the inner ends of the opposed screws 1Q, let, '16 and 18, which are threaded in binding posts 20, 21, 22 and 23,-respectively, and provided at their outer ends with knutled hea-ds 24, by means ot which they may be adjusted to vary the limit of throw of saidarms. The free ends ot' the armsl 4 and 6 may be p vided with weights 26 adjustably mounted on springsl ,t28 secured to said arms. The purpose of these resilicntly .supported weights is .to quicken theI action of the separation ot" the contacts 7, 8, 9, and 10 from their respectively opposed screws, when the contact-carrying bratcd as will be hereinafter Iexplained.

The switch l is oscillated by means of a pair ot' opposed electromagnets 30 and 31,-

having a com-mon armature 32 carried by ay metallic arml mounted on the insulating:I block 2. A pair ot' resllient contacts 3G and 3S arejinounted on opposite sides of the arm 3l and are adapted to be brought into con# tact with the opposing ends of the screws l-O and l2, respectively, threaded in the binding posts lst and 4G, respectively, and provided at their outer ends with knltrled heads 4S, by means of which they miayibe adjusted with relation to the contacts 3G and 3S to vary the speed with which the arina ture will be vibrated. f

The direct current. enters through the conductor 50 and leaves through the conductor 5l. 'lhe conductor 50 is connected by the conductors 52 and 53 with the post` Q0. `A conductor 5l connects the junction of the conductors 52 and 53 with the post Q2; a conductor 5ft connects the posts and 21; and a conductor 5U connects the post 2l with the conductorll.

The magnets :30 and 3l are connected in a shunt circuit: which may be provided with a variable resistance 57. Ity will be under-- stood however that'y the magnets may be operated by an independent source of electrical energy it' desired. A conductor 5S connects the conductor with one end `ot the magnet coil 30, and the other end of said coil is connected 'by a conductor 59 to the post 4G. A conductor 60 connects the. conductor 52 with one end of the magnet coil arms are oscillated or vi- 8i, and the lother end of 'said coil is con-v nected by conductors Gl and G2 to the post 4st.

A conductor G3 connects the arm 3l with the conductor 5l through the variable resistance Condensers ('5 and GG are connected between the posts stl and 4G, respec- -ctliciency of closed-core transformers andA tively, and the magnet circuit, that is, across the inake-and-break contacts, to reduce the spark when this circuit is broken at the contacts 3o and 38.

The alternating current work-circuit is connected to the conductors` and 7l at. tached to binding posts 72 and 74 respectively, which in turn are vconnected to the contact-carrying arms si and 6 by conductors 7() and 78. Condensers 8O and 81 are connected between the posts 72 and 7st, respectively, and the conductor 5st; and condensers and 83 are connectedbetween the posts 72 and 7st, respectively, and the conductor oa. decrease the spark at the switch contacts at each break ot' the alternating current, and to increase the spark with induction coil or transformer at each break of the circuit. This is especially desirable in wireless telegraphy and X-ray work. It increases the increases the sending distance of open-core transformers when` used in wireless telegrapliy.

'the operation of the device is as follows: The direct'current entiers through the conductor 50 and a 'portion of the current is sl'iunted through the magnet circuit. The contact 38 may be held against the sci-ew #l2 by a spring 43 attached to the disk 2 in order to start the device. The/current then passes through the conductors-52, 58, mag net coil 30, conductor 59, post flo, screw 42,

contact 38, arm 34, conductor 63, and the' variable resistance 57 to the conductor 5l. 'lhe resistance 57 may be regulated to allow any desired amount of current to pass through the@ shunt to energize the magnets Il() and 3l. The magnet 30 being energized draws the armature 32 toward the right and oscillatcs the support 2 and the contact arms t and o, so that the contact 7 is brought into engagement with the' screw 12, and the contact l() is brought. into engagement with thc screw 18. dit this moment the current flows through conductors 50, 52, 53, post 20, screw 12, contact 7, arm 4, conductor 76, post 72, conductor 70 to the alternating enrrent work-circuit and returns through the. conductor 7l., post 711-, conductor 78, arn'i ti, contactI l0, screw 18, post 23, conductor 55, post 2l, conductor 5G, to the conductor 5l. its the armature 32 is drawn toward the right the circuit is broken between the contact 38 and the screw ft2, and the circuit is closed between the contact 36 and the screw 4:0. Thereupon the magnet 30 is dconergized and the magnet 31 is energized. The armarhe purpose of these condensers is tov ture 32 is now drawn to the left and the diskv 2 is oscillated to bring the contact 9 into engagement with thc screw 16 and the contact S in engagement with the screw 14. At this time the current passes from the conductor 50 through the conductors 52, 5l, post 22, screw .16, contact 9, arm 6,'eonductor 78, post 74e and conductor 7l to the alternating current work-circuit, and returns through the conductor 70, post 72, conductor 76, arin il, contact 8, screw 1st, post 2l, and lconductor 5G to the conductor 5l, It will thus be seen that at each vibration of the armature 32 the direction of tlic current through the alternating current work-circuit is reversed. The rapidity or' these alternations can be varied by varying the speed at which the magnet circuits are interrupted. By using the' condensers as shown thes'parks of induction coil or transformer are increased at each break of the circuit and in each alternation. l

Vhile we have illustrated and described a preferred embodiment of the invention, we are aware that Vmany modilications can be made by any person skilled in the art without departing from the scope of the invention as expressed in the claims. Therefore we do not wish to be limited to .ill the details of construction shown and described, but

What we claim is:- l. In a device of the class described, the combination .with a supply of direct current,

of a switch comprising a pivoted insulatinghaving three arms mounted thereon and rac ,liating from the pivotal center thereof, an

y armature carried by one of said arms, a pair of make-and-break contacts cooperating with the armattire-carrying arin, a pair ot' switch contacts on each of theotlicr two arms, adjustable stationary contacts opposed to the contacts on said arms, and opposed electromagnet coils cooperating with said armature for rapidly oscillating the arnis'betwccn the switch contacts.

3. In a device of the class described, the combination with a supply oli direct current, of a vswitch comprising a pivoted insulating vblock having three arms mounted thereon and radiating from the pivotal center thereof, an arn'iature carried by one ot said arins, electi'on'iagnetic means energized by said d1- rect current for cooperating with said arniature to oscillate said block, make-uiitl-break contacts in the circuit of said electromagwith one of said armsf switch contacts carried by each .netic means,

condensers connected across said make-and-break contacts, av pair of of the other two brins, adjustable stationary contacts cooperating with said switch contacts, and a condenserconnected across each pair of cooperating switch contacts.

In testimony whereof we have signed our STRATFORD Bf ALLEN. EVERETT T. KING.

Vitnesses:

CHARLES F. HOWE, GEORGE CLARENDON HoDGEs. 

